when using cros-workon packages on internal repos (like a minilayout manifest), the git calls from cros-workon don't include the necessary git credentials which leads to failures:
cr50-utils-0.0.1-r4:  * Existing git repo corrupt, removing and initialing clean checkout in /var/cache/chromeos-cache/distfiles/host/egit-src/chromeos/platform/cr50-utils
cr50-utils-0.0.1-r4: Cloning into bare repository '/var/cache/chromeos-cache/distfiles/host/egit-src/chromeos/platform/cr50-utils'...
cr50-utils-0.0.1-r4: fatal: could not read Username for 'https://chrome-internal.googlesource.com': No such device or address
cr50-utils-0.0.1-r4:  * ERROR: chromeos-base/cr50-utils-0.0.1-r4::chromeos failed (unpack phase):
cr50-utils-0.0.1-r4:  *   git-2_initial_clone: can't fetch from https://chrome-internal.googlesource.com/chromeos/platform/cr50-utils.git

we copy creds over by hand in the chromeos-chrome ebuild, but that's the only place (see src_unpack and netrc/gitcookies logic).  we should make cros-workon (at least) smarter and copy the necessary files over to the portage environment.